Lactic acid removal and demineralization of acid whey by coupling electrodialysis under pulsed electric fields with pre-concentration by nanofiltration: impact on spray drying and powder quality
Bibliographic record
Abstract
Acid whey is a liquid by-product generated after acid precipitation during the production of fresh cheese and Greek yogurt. Its valorization has become a critical issue, as acid whey is considered one of the largest waste streams in the dairy industry. The high lactic acid and calcium content of acid whey limit the drying process required for its valorization, necessitating its pre-treatment. In this study, the coupling of nanofiltration (NF) with electrodialysis (ED) under pulsed electric field (PEF) conditions was explored. ED under two PEF conditions, PEF 5 s/5 s and PEF 15 s/15 s, was compared to ED under continuous current (CC). Prior to ED treatments, acid whey was concentrated (4.33 ± 0.41×) by NF, resulting in increases in the concentrations of calcium, magnesium, lactic acid and lactose by 46.7 %, 93.3 %, 25.8 % and 164.1 %, respectively. The ED treatments were performed until 70 % demineralization was achieved, during which 46.3 % of the lactic acid was recovered from acid whey, with no differences observed among the conditions tested ( p > 0.05). A greater removal of calcium and magnesium was achieved using PEF 5 s/5 s ( p < 0.05), resulting in 35.1 and 47.0 % higher removal compared to CC, respectively. The removal of lactic acid and divalent ions by coupling NF and ED under CC improved the drying yield by 13.75 percentage points compared to NF alone. The improvement was further amplified when coupling NF and ED under PEF 5 s/5 s, achieving a drying yield of 90.35 ± 1.74 %. This represents an 18.86 percentage point increase compared to NF alone and a 5.11 percentage point increase compared to NF coupled with conventional ED. Powder quality analysis after spray drying revealed that PEF 5 s/5 s effectively reduced the hygroscopicity of the powders. These results demonstrate for the first time the promising potential of improving acid whey drying and yield by coupling NF and ED under different PEF conditions. Furthermore, the valorization of organic acids and minerals recovered from the acid whey could pave the way for exploring circular economies (CE) in the future.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".